chore(travis): trying to support Node 0.11.x (and forthcoming 0.12.x)
chore(gulpfile): rename 'webserver' task to 'serve'
fix(empower): bugfix: power-assert output doesn't appear in Node 0.11.x

Error#stack is set in AssertionError constructor function.
So I need to instantiate another AssertionError to replace stack.
chore(empower): rebuild web bundle
refactor(empower): always re-instantiate AssertionError on rethrow
refactor(empower): inline assignments
Merge pull request #13 from twada/node-0_11_x

Support Node 0.11.x (and forthcoming 0.12.x)